Non-palpable lesions of the breast detected by mammography--review of 1182 consecutive histologically confirmed cases.

We report on 1182 consecutive histologically confirmed non-palpable breast lesions detected by mammography (infiltrating carcinoma 427, in situ carcinoma 121, benign 634). The proportion of cancer cases varied according to age (< 50 years = 33%; 50-59 years = 46%; > 59 years = 63%), mammographic pattern (regular opacities = 8%, parenchymal distortions = 20%, isolated calcifications = 42%, irregular opacities = 62%, stellate opacities = 73%), and calendar period (1970-1985 = 29%, 1986-1989 = 56%; 1990-1992 = 69%). A sharp decrease of the benign/malignant biopsy ratio was evident after routine fine-needle aspiration cytology (sonography-guided or stereotaxic) was introduced in 1986. The independent significant association of cancer frequency to age, calendar period and mammographic pattern was confirmed by multivariate analysis. A significant trend over time in favour of conservative surgery was also observed for cancer cases (1970-1979 = 6%, 1980-1985 = 41%, 1986-1992 = 83%). Among invasive cancers, node involvement was observed in 11.5% of cases, being associated with tumour size (pT1a = 0%, pT1b = 7%, pT1c = 13%, pT2a = 33%). Five-, ten- and fifteen-year overall survivals of invasive cancers were 98.1, 95.7 and 87.3%, respectively.